Effects of H2 plasma treatment on properties of ZnO:Al thin films prepared by RF magnetron sputtering

Al-doped ZnO (AZO) thin films were prepared on glass substrates by radio-frequency magnetron sputtering at deposition temperatures ranging from room temperature (RT) to 300 °C for transparent electrode applications. This study investigates the effects of H2 plasma treatment on structural, electrical, and optical properties of AZO thin films. Plasma treatment was conducted at 300 °C using a plasma-enhanced chemical vapor deposition system for potential large size substrate applications. The crystal structure of plasma treated AZO films did not change considerably, but the surface roughness and surface grain size increased slightly. Improvement in electrical properties was strongly dependent on the deposition temperature. When the deposition temperature ranged from 300 °C to RT, the resistivity of plasma treated films decreased significantly by 22.7% to 97.6%, and the optical bandgap broadened by 0.011 to 0.076 eV.

Research highlights
► We study effects of H2 plasma treatment on AZO sputtered at various temperatures.
► H2 plasma treatment improves markedly the opto-electrical properties of AZO films.
► The improvement in resistivity is dependent on deposition temperature of AZO films.
► Hydrogen plasma treatment broadens of the optical energy bandgap of AZO films.
► The chemical structure of plasma treated AZO films is investigated by XPS.